Automatically vented fluid pressure operated apparatus



July 16, 1957 CQNRAD' 2,799,343

AUTOMATICALLY VENTEb FLUID PRESSURE OPERATED APPARATUS Filed June 20,1955 2' Shets-Sheet-l mm M WM m m6 M Z July 16, I957 M. B. CONRADAUTOMATICALLY VENTED FLUID PRESSURE OPERATED APPARATUS Filed June 20'."1955 2 Sheets -Sheet 2 a i 22 L M Q l 3 v k 0 7 u m6 r w E .f .54 a \T IIII M .I .i 111! ll .1 I a 5% i M m H v z a .x 2%. Wfl M W 3m H H a 5 3I ll i 1 l 9 9 a n w L in. my .9 www ite AUTOMATICALLY VENTED FLUIDPRESSURE ()PERATED APPARATUS Application June 20, 1955, Serial No.516,478

6 Claims. (Cl. 166-63) The present invention relates to subsurfaceapparatus adapted to perform certain desirable operations in oil, gasand similar oil wells.

Certain types of well apparatus are operated in well bores by utilizinga gaseous medium under pressure to supply the necessary motivatingforce. As an example, a well packer may be set in a well bore throughthe exertion of a gaseous force thereon that might be present in asetting tool attached to the well packer, the setting tool beingreleased from the latter after it has been set.

Heretofore, care had to be exercised in disassembling the setting toolafter it has been retrieved from the Well bore to assure release andbleeding off of the gas pressure trapped within the tool. At times,which fortunately occurred very infrequently, dismantling of the settingtool has been attempted improperly without first releasing the gaspressure in the tool, allowing the gas pressure to forcibly and suddenlyseparate the partially dismantled tool parts, and possibly injuringpersons or damaging property.

Accordingly, it is an object of the present invention to provide gaspressure operated subsurface apparatus, of improved and comparativelysimple construction, from which the gas pressure is releasedautomatically following the performance of the required operations inthe well bore, thereby eliminating the danger of accident when theapparatus is dismantled improperly following its removal from the wellbore.

Another object of the invention is to provide a setting tool for a wellpacker to be set in a well bore, in which the setting tool is operatedby gas pressure, and in which the gas pressure is released automaticallyafter the well packer has been set, the gas pressure release feature ofthe setting tool being of simple, strong and sturdy construction, andeasy to assemble, disassemble and maintain in proper operatingcondition.

A further object of the invention is to provide a gas pressure operatedapparatus for use in a well bore in which the gaseous force is exertedupon a piston structure disposed within a confining cylinder, and inwhich an improved by-pass around the piston is provided to release thegas under pressure into the surrounding Well bore after the apparatushas performed its desired function in the well bore.

This invention possesses many other advantages, and has other objectswhich may be made more clearly apparent from a consideration of a formin which it may be embodied. This form is shown in the drawingsaccompanying and forming part of the present specification. It will nowbe described in detail, for the purpose of illustrating the generalprinciples of the invention; but it is to be understood that suchdetailed description is not to be taken in a limiting sense, since thescope of the invention is best defined by the appended claims.

Referring to the drawings:

Figures 1, 1a and 1b together constitute a longitudinal section throughwell apparatus positioned in a well casatent I ing, Fig. 1b forming alower continuation of Fig. la, and

Fig. 1a forming a lower continuation of Fig. 1, the parts occupying aposition in which the well packer portion of the apparatus has beenanchored in packer-oft condition in the well casing,

Fig. 2 is an enlarged longitudinal section through a portion of theapparatus for releasing the pressure therewithin, the parts occupyingthe position just prior to release of the pressure;

Fig. 3 is a longitudinal section similar to Fig. 2, disclosing the partsin the position they occupy when the pressure has been released.

The invention is shown in the drawing as applied to a setting tool Creleasably secured to a well packer A anchored in packed-off conditionagainst the well casing B, the setting tool being attached to the lowerend of the running-in string D, such as a wire line, extending to thetop of the well bore. It is to be understood, however, that theinvention has wider applications than is specifically disclosed, andthat the setting of the well packer is merely illustrative of theinvention.

The apparatus disclosed in the drawings may take the form specificallydescribed and illustrated in the patent to Martin B. Conrad, 2,618,343,patented November 18, 1952, for Gas Pressure Operated Well Apparatus, towhich attention is directed for certain details of construction andrelative locations of parts which are not specifically disclosed in thepresent application. In both the patent and the present application, awell packer A is shown anchored in packed-off condition within a wellcasing. This well packer includes a tubular main body 10 whose centralpassage 11 may be closed by a plug 12. A guide 13 is secured to thelower end of the body to prevent the tool from catching or hanging up inthe casing or coupling spaces during its lowering in the well casing B.

The well packer has been anchored against downward movement in the wellcasing by a plurality of lower segmental slips 14 engaging the guide 13and the lower abutment or flange 15 on the body. The inner surfaces 16of the slips are tapered in a downward and inward direction for slidableengagement with a corresponding or externally tapered surface 17 on afrusto-conical expander 18 slidable on the body. This expander isconnected to the lower end of a packing sleeve 19 of rubber or similarmaterial disposed around the body 10, the upper end of this packingsleeve being connected to an upper expander 20 having an upwardly andinwardly inclined externally tapered surface 21 having wedgingengagement with corresponding tapered surfaces 22 on a plurality ofupper segmental slips 23.

Initially, the slips 14, 23 and packing element .19 are retained inretracted position with respect to the packer body 10. Shear screws 24,25, or other suitable frangible connecting elements, secure the upperand lower expanders 2t), 18 to the body, with the intervening packingsleeve held in retracted position. The upper and lower slips 23, 14 arealso held in retracted position by shear screws 26, 27 attaching them totheir associated upper and lower expanders 2t), 18.

The shear screws 26 attaching the upper slips 2?: to the upper expander2% have a combined shear strength which is substantially less than theshear value of the screws 24 holding the upper expander to the body 10.These latter screws have a lesser shear value than the screws 25, 27securing the lower expander 18 to the body and the lower slips 14 to thelower expander. These relative shear values are selected to securedetachment, at first, of the upper slips 23 from the upper expander 20,and the movement of the upper slips downwardly along the upper expanderand radially outward into anchoring engagement with the casing wall. Asubsequent upward strain or pull on the packer body shears the screws 24holding the upper expander to the body and moves the lower expander 13and slips 14 with the body toward the upper expander 20 and slips 23, toeffect compression of the packing 19 between the expanders and itsoutward expansion into firm sealing engagement with the wall of thecasing.

Thereafter, an increase in the upward pull or force on the packer body10 substantially simultaneously shears the screws 25, 27 holding thelower expander 18 to the body and the lower slips 14 to the lowerexpander, to cause the lower flange l5 and guide 13 on the body to shiftthe lower slips 14 upwardly along the lower expander and radiallyoutward into anchoring engagement with the wall of the casing B. A splitretractor ring 28 may be disposed in the expander 2%) for engagementwith one of several buttress thread ratchet teeth 29 formed on theexterior of the body ill to lock the latter against downward movement.The packer is now anchored in packed-cit condition within the wellcasing, as disclosed in Fig. 112.

As shown in the drawings, setting of the Well packer A is dependent uponthe development of a gas pressure within the setting tool C releasablysecured initially to the well packer. This gas pressure is developedwithin the upper portion of a cylinder 30, consisting of a generallycylindrical upper sleeve 31, an upper head 32 threaded into this sleeveand also an intermediate head 33- threaded into this sleeve. A lowercylinder sleeve 34 is threadedly secured on the intermediate head 33 andis, in turn, threaded onto a lower cylinder head 35.

The upper head 32, upper sleeve 31 and intermediate head 33 form anupper cylinder portion 30a, whereas the intermediate head 33, lowercylinder sleeve 34 and lower head 35 form a lower cylinder portion 30b.These two cylinder portions 30a, 30b are separated by the intermediatehead 33, but are communicable with each other through a central passage36 formed through the intermediate head. Leakage from the cylinderthrough the several threaded connections may be prevented by suitableside seals 37 in the heads 32, 33, 35 engaging the inner walls of thecylinder sleeves 31, 34.

A motivating gas under pressure is provided in the upper cylinderportion 30a, and the force of this gas is transmitted through a suitableliquid medium 38 to the lower cylinder portion 30b through theintermediate head passage 36 for operation upon a piston 39 slidablymounted in the lower cylinder portion. This piston 39 has one or morering grooves 43 in its periphery for the accommodation of seal rings 41to prevent leakage in both directions between the piston 39 and lowercylinder sleeve 31.

The upper end of a piston rod 42 is threadedly connected to the piston39, the rod extending downwardly through the lower cylinder head 35 to apoint therebelow. An anvil or cross-piece 43 is mounted within atransverse slot 44 in the rod. Leakage between the rod 42 and lowercylinder head 35 is prevented by suitable rod packing 45 disposed withinsuitable ring grooves 46 in the head 36, to prevent leakage of liquidsfrom the well easing into the cylinder 33b below the piston 39, insuringthat air under atmospheric pressure is present below the piston when theapparatus is assembled and lowered in the well casing B.

It is desired to transfer the downward movement of, or force imposedupon, the piston 39 and the piston rod 42 to the upper slips 23 of thepacker body 10, to secure the desired anchoring of the packer in thewell casing. To accomplish this purpose, a tubular actuating mandrel 47is threadedly connected to the lower end of the lower cylinder head 35.The lower end of the mandrel 47 is secured, through the agency of thefrangible connecting pins 48, to a sleeve 49 threaded to the upper endof the body 10. As specifically disclosed, the

lower end of the mandrel 47 is of reduced diameter and is piloted withinthe sleeve 49, the pin 48 extending transversely through the sleeve andpilot mandrel portion.

The piston rod 42 is movable downwardly within the bore 50 of theactuating mandrel 47, the cross-piece 43 projecting in oppositedirections from the rod through diametrically opposed longitudinallyextending slots 51 formed through the mandrel wall. The cross-piece alsoextends through opposed slots 52 formed through a setting ring or sleeve53 slidably mounted on the actuating mandrel 47 to form a connectionbetween the piston rod 42 and the cross-piece 43. A setting sleeve orskirt 54 is adjustably threaded on the setting ring 53, its lower .endengaging the top of the upper slips 23.

As indicated above, a force or pressure is imposed on the liquid 38,such as oil or water, resting on top of the piston 39. This force movesthe piston 39 and piston rod 42 downwardly and the cylinder 30 in a relatively upward direction. The downward movement of the rod 42 istransmitted to the setting sleeve or skirt 54 through the anvil 43 andsetting ring 53, whereas the upward movement of the cylinder 30 istransmitted to the packer body 10 through the actuating mandrel 47,frangible pin 48 and sleeve 4-9. Accordingly, it is apparent that thedevelopment of suiiicient pressure in the cylinder 30 acting upon thepiston 39 will eventually shear the screws 26 holding the upper slips 23to the expander 20 and move the slips outwardly against the casing B.Thereafter, the cylinder 39 will move upwardly to pull the body it inthe same direction for the purpose of expanding the packing sleeve 19against the casing B and the lower slips 14 against the casing, in themanner described above.

To secure the desired operational sequence, gas under pressure isprovided within the upper end of the cylinder 30. Such gas underpressure may be generated in the upper end of the cylinder, as byburning a combustible charge 60 in the cylinder. As specificallyillustrated and described in Patent 2,618,343, the charge is ignited bya blank cartridge 61 contained within a gun barrel 63 inserted withinthe upper end of the upper cylinder head 32. Leakage between the barreland the cylinder head is prevented by a suitable side seal 64 in thebarrel engaging the wall of the head 32. This barrel 63 is threaded intoa firing head 65 which, in turn, is threadedly se cured to the upper endof the cylinder head 32. The wire line running-in string D is suitablysecured to the firing head, in a known manner, and has the lower end ofits electrically conductive wire or core 66 connected electrically to aheating filament 67 contained within the cartridge 6.

When the combustible fuel or power charge 60 is ignited, evolved gasunder pressure is produced within the upper end the upper cylinderportion 30a, or some other form of gas under pressure may be providedtherein. This gaseous force acts downwardly upon an upper or floatingpiston structure 70 disposed initially adjacent the upper cylinder head32. The piston portion 71 of this structure carries one or more suitableseal rings 72 in one or more peripheral grooves 73 that are engageablewith the wall of the upper cylinder sleeve 31 to prevent leakage aroundthe exterior of the piston in both directions.

Originally, as disclosed in Patent 2,618,343, the piston structure 70rests upon the fluid medium 38, which substantially entirely fills thecylinder space between the upper piston structure and the lower piston39, including the volume of the passage 36 through the intermediatehead. This fluid medium is predominantly and almost entirely a liquid,such as water or oil. For the purpose of delaying a transfer of theliquid medium 38 from the upper cylinder portion 30a into the lowercylinder portion 30b as the floating piston structure 79 is forceddownwardly by the gaseous pressure in the upper portion of the cylinder30a, a flow restricting device 74, such as a bean or orifice, isthreaded into the lower end of the passage 36 through the intermediatehead 33. The cross-sectional area of the hole 75 through the bean ororifice 74 is much less than the area of the passage 36 itself, theorifice area being so chosen as to allow fluid to flow from the uppercylinder 30a into the lower cylinder portion 30b for action upon thelower piston at a slow or retarded rate, for a purpose to be explainedbelow.

The apparatus is lowered in the well bore with the slips and packingelements of the well packer disposed in their initial retractedposition, with the lower piston 39 adjacent the lower end of theintermediate cylinder head 33 and with the floating piston structure 70in its upper position adjacent the upper cylinder head. The oil or water38 substantially completely fills the cylinder between the upper pistonstructure 70 and the lower piston 39.

When the depth in the casing is reached at which the well packer A is tobe set, the electric circuit through the cartridge filament 67 iscompleted to fire the cartridge 61. The flame issuing therefrom ignitesthe upper end of the combustible charge 60 resting upon the upper pistonstructure 70, initiating its combustion. This charge contains its ownsource of oxygen to support combus tion. As combustion proceeds, agaseous pressure is developed within the upper portion of the cylinder30a above the floating piston structure 70. As the pressure increasesthe floating piston structure is urged downwardly and the cylinder 30relatively upwardly. The force imposed on the floating piston structure70 is transmitted through the fluid medium 38 to the lower piston 39,and from this piston through the rod 42, cross-piece 43 and settingsleeve 53 to the sleeve 54, which bears against the upper slips 23.Downward movementof the lower piston 39 takes place against therelatively slight resistance of the air in the lower cylinder portion30a below the piston 39, which is initially at atmospheric pressure, andalso against the hydrostatic head of fluid in the well casing actingupwardly across the cross-sectional area of the piston rod 42. Whensufiicient pressure has been developed within the upper cylinder portion30a by the gaseous medium and has been transmitted through the pistonstructure 70, fluid medium 38, lower piston 39, piston rod 42,cross-piece 43, setting ring 53, and sleeve 54 to the slips 23, toovercome the shear strength of the shear screw 26, and also thehydrostatic head of fluid acting upwardly on the piston 42, the slips 23are released from the expander 29 and are pushed downwardly along thelatter into outward engagement with the casing B.

As the combustible charge 60 continues to burn, the gas pressure withinthe upper cylinder portion 30a progressively increases to a furtherextent, and the increased pressure and force is transmitted to the lowerpiston 39 through the intervening fluid medium 38. Since the upper slips23 are wedged against the casing B, the piston 39 cannot move downwardlyto an further appreciable extent. Instead, the cylinder 3%, actuatingmandrel 47, sleeve 19 and packer body are urged in an upward direction.When the pressure and force within the cylinder 3%? is increasedsufficiently to overcome the shear strength of the screws 24 holding thethe upper expander 2t? to the body, such screws are disrupted and thepacker body is then moved upwardly within the upper expander 26 tocompress the rubber packing sleeve 19 between the upper and lowerexpanders 2t), 18, forcing the packing sleeve into 'firm sealingengagement with casing wall.

Further increase in the cylinder gas pressure, as a result of thecontinued combustion ofv the charge 66, eifects shearing of the screws25, 27 attaching the lower expander 18 to the body 10, and the lowerslips'14 to the lower expander, allowing the cylinder 30 to moveupwardly and carry the body It) and lower slips 14 in an upwarddirection to shift the latter radially outward into engagement with thecasing B.

The pressure in the cylinder 30 continues to increase as combustion ofthe charge proceeds, and all of the packer elements are engaged morefirmly with the casing B (as disclosed in Fig. lb). When the pressureexceeds the shear strength of the connecting pin 48 securing the lowerend of the actuating mandrel 47 to the sleeve 49, this pin is sheared torelease automatically the setting tool C from the well packer A. All ofthe mechanism, with the exception of the packer A can now be removedfrom the well casing B.

The orifice 74 retards the downward movement of the floating pistonstructure 70 in the cylinder as the gas pressure increases and as thesequence of operation on the well packer takes place, so that no suddenmovements can occur, particularly the sudden descent of the pistonstructures 70, 39 relatively within the cylinder 30 following disruptionof the shearable connector pin 48. When this occurs, the upper pistonstructure 70 can only move downwardly at a relatively slow rate (whichmay consume several seconds) until the piston structure 78'' engages theintermediate cylinder head 33. The lower piston 39 will only movedownwardly to the extent determined by the volume of liquid 38thereabove that has been forced through the orifice 74 into the lowercylinder portion 30b. Accordingly, the parts of the apparatus will cometo rest without any sudden shock blows being struck against portions ofthe cylinder 30, which might damage the apparatus. However, the uppercylinder 30a above the piston structure 70 will still contain gas underrelatively high pressure (which may be as high as 7500 p. s. i.) whichpressure could remain trapped within the cylinder until the setting toolC is withdrawn from the well bore to the top of the hole. Extreme caremust be exercised in releasing this gas pressure at the top of the hole,during disassembly of the setting tool, to obviate a dangerous conditionand to prevent injury to persons and damage to property.

Following the disruption of the shear pin 48 connecting the setting toolC to the well packer A, which actually completes the operation in thewell bore with the specific apparatus illustrated, it is desired toautomatically vent or bleed the pressure within the upper cylinder 30ainto the surrounding well bore. It is also a desirable feature to bleedthe liquid 38, or relieve the pressure in the liquid, disposed in thecylinder 30 into the surrounding well bore, so that the removal of thesetting tool C to the top of the hole can occur with assurance thatthere is substantially no fluid pressure within the cylinder 30.

As disclosed, the upper piston structure 70 is of a composite character.It includes a central piston portion 76 from which a stem or rod 77depends to asubstantial extent. The periphery of the central portion 76is disposed a substantial distance inwardly from the wall of the uppercylinder. The piston construction includes the outer piston portion orshell 71 which slidably seals against the wall of the upper cylinder, asheretofore described. The inner surface 78 of the hollow piston shell 71is adapted to seal against the upper peripheral portion 79 of the pistonrod 77 when the piston shell is disposed in its uppermost positionsubstantially abutting the central piston portion 76. Thus, the pistonshell is adapted to seal against a suitable seal ring 80, such as arubber O ring, contained within a peripheral groove 81 in the pistonstem.

The piston shell 71 has an upwardly extending skirt 82 encompassing thecentral piston portion 76 and slidable along the cylinder wall. Thisskirt is preferably spaced outwardly from the periphery of the centralportion 76 to allow the gas pressure in the upper cylinder 30a above thepiston structure 70 to be exerted between the opposed faces 76a, 71a ofthe central piston portion and the piston shell. To assure that fluidunder pres- 7 sure can be exerted on the upwardly facing surface 71a ofthe piston shell, the central piston portion 76 may be provided with aplurality of longitudinal passages 83 extending from its upper surfaceto its downwardly facing surface 76a.

As described hereinbelow, when the piston shell 71 is moved downwardlyalong the piston stem or rod 77, its inwardly projecting surface '78will ride off the upper sealing portion 79 of the stem or rod and cometo rest in a position therebelow. At this time, a by-pass passage 84will be opened through the piston structure '70, the fluid in thecylinder 39a above the piston structure 70 being capable of passingaround the periphery of the central piston 76, and between the centralportion and the upper end of the piston shell 71, thence between theperiphery of the stem 77 and the interior of the piston shell 71 to alocation below the piston structure 70. The piston shell 71, in effect,is a valve member adapted to be disposed in an upper position in sealingengagement with the piston rod seal ring 80 to close the by-pass 84.When moved downwardly, as has just been described, the by-pass isopened.

The piston rod 77 depends to a substantial extent below the piston shell71, being adapted to operate upon an internal sleeve valve 85 locatedwithin the intermediate head passage 36, for the purpose of shifting thesleeve valve downwardly to an open position. Initially, this sleevevalve 85 is disposed across one or more relief or bleeder ports 86extending through the intermediate cylinder head 33 between its passage36 and the exterior thereof. The sleeve 85 has a central passage 87therethrough surrounded by an upwardly facing tapered valve seatingsurface 88. When the valve 85 is disposed across the bleeder ports 86,leakage between the wall of the passage 36 and the periphery of thesleeve is prevented by one or more side seals 89 disposed in peripheralgrooves 90 in the sleeve and sealingly engaging the wall of the passage36 on opposite sides of the bleeder ports 86. The sleeve valve 85 isreleasably retained in this initial position by a latch device, whichmay take the form of a split, expansible latch ring or snap ring 91located within a peripheral groove 92 in the sleeve and normally tendingto be disposed outwardly into an internal groove 93 in the intermediatecylinder head. Both the latch ring 91 and the internal groove 93 haveopposed tapered side walls 94, 95 that converge toward each other in alateral outward direction to facilitate inward retraction of the latchring 91 when the sleeve valve member 85 is to be shifted downwardlywithin the intermediate head passage 36.

In the use of the apparatus, the upper piston structure 70 movesdownwardly as a unit as the gas pressure increases in the upper cylinder3% thereabove, forcing the liquid 38 down through the intermediate headpassage 36, the orifice 74 at its lower end, and into the lower cylinder3% for action upon the lower piston 33, to secure the full setting ofthe well packer A in the well bore. When the release or shear pin 48 isdisrupted, the apparatus is relieved of load, which then allows theupper piston structure 70 to move downwardly to a further extent, thelower end 96 of the rod or stem entering the intermediate head passage36 and coming to rest on the valve seat surface 88 of the sleeve valve85. During all of this time the piston shell '71 remains in itsuppermost position against the central piston portion '76, so that thegas under pressure above the upper piston structure 7% cannot by-passaround it. As the piston structure 7 moves downwardly after engaging thevalve sleeve 85, it effects an inward retraction and release of the snapring 91 from the intermediate head groove 93, pushing the sleeve valve85 downwardly to its fullest position below the relief or bleeder ports86, opening the latter and establishing communication between theintermediate head passage 36 and the surrounding well bore.

When the inner sleeve valve engages the intermediate head at the lowerend of the passage 36, the sleeve valve 85 and the piston rod 77 cannotmove downwardly to any further extent. However, the gas under pressureis still acting on the piston shell 71, which at that time is stilldisposed above the upper end of the intermediate head 33. This gas underpressure then shifts the piston shell 71 downwardly relative to thecentral piston portion 76 and the rod 77, to shift its inwardly directedvalve portion 78 off the seal ring 80 on the rod and into a position inwhich the by-pass 84 through the shell 71 is opened, such as disclosedin Fig. 3. With the parts in this position, the gas under pressure canthen pass from the upper cylinder a above the piston structure 70,between the piston shell 71 and the central piston portion '76 and therod 77 into the intermediate head passage 36, making its exit throughthe relief ports 86 into the well bore. Following the venting of thegas, the liquid 38 under pressure in the lower cylinder 3% can thenexert a force in an upward direction to lift the stem 77 off the valveseat 88, which will then allow the liquid to pass through the sleevevalve 85 and out through the relief ports 86 to the exterior of theapparatus.

It is preferred that the lower end 96 of the piston rod 77 make a sealwith the valve seat 88 in the inner sleeve valve 85, so that as a resultof the initial engagement of these parts, no further liquid below theupper piston structure can be forced down through the sleeve valve andinto the lower cylinder 30b. In effect, the liquid will tend to betrapped between the upper end of the sleeve valve 85, when the latter isdisposed in its closed position, and the lower portion of the pistonshell 71. Accordingly, the full force of the gas under pressure actingdownwardly on the upper piston structure 70 is available to shift thesleeve valve 85 downwardly, which will insure the retraction of the snapring 91 completely within the sleeve valve groove 92, and assure thedownward sliding of the sleeve valve to its lowermost position, in whichthe relief ports 86 are open. If, for some reason, the stem or rod 77does not move downwardly following its engagement with the sleeve valve85, then the piston shell 71 will move downwardly along the rod 77 toexert the pressure on the liquid therebelow and cause the liquid underpressure to act downwardly on the sleeve valve 85 and effect theretraction of the snap ring 91 and the downward shifting of the sleevevalve 85 to the bleeder port opening position. As a matter of fact, thesleeve valve 85 need not move downwardly slowly. Upon release of thelatch ring 91, it can, in effect, be impelled to its downward position,remaining in such downward position because of the friction of the sealrings 89 and of the snap ring 91 against the wall of the passage 36.

With the apparatus disposed in the fluid in the well bore, the fluidpressure will diminish to the extent corresponding to the hydrostatichead of fluid in the well bore. As the setting tool C is raised throughthe fluid in the well bore, and the hydrostatic head acting thereuponprogressively decreases, the pressure within the apparatus will also becorrespondingly decreased until it is substantially zero when theapparatus is removed from the well at its top portion. The apparatus canthen be dismantled, with assurance that there is no substantial pressurewithin the equipment that could injure persons or impose damage toproperty.

The inventor claims:

1. In well apparatus for operation in a well bore: a cylinder; a pistonstructure in said cylinder; means adapted to provide a fiuid underpressure in said cylinder on one side of said piston structure to shiftsaid piston structure in said cylinder; said cylinder having a passageon the other side of said piston structure extending from the interiorof said cylinder to its exterior; shiftable valve means closing saidpassage; said piston structure including an inner portion engageablewith said valve means to shift said valve means to passage openingposition; said piston structure including an outer portion; said innerand outer portions being constructed and arranged to provide a by-passtherebetween when said portions are in one position relative to eachother through which said fluid under pressure can pass for dischargethrough said passage; said outer portion being movable by said fluidunder pressure relative to said inner portion to such relative positionto open said by-pass.

2. In well apparatus for operation in a well bore: a cylinder; a pistonstructure in said cylinder; means adapted to provide a fluid underpressure in said cylinder on one side of said piston structure to shiftsaid piston structure in said cylinder; said cylinder having a passageon the other side of said piston structure extending from the interiorof said cylinder to its exterior; shiftable valve means closing saidpassage; said piston structure including an inner central portionengageable with said valve means to shift said valve means to passageopening position; said piston structure including an outer portion inslidable sealing engagement with said cylinder and adapted to be insealing relation to said inner portion to prevent fluid flowtherebetween; said inner and outer portions being constructed andarranged to provide a by-pass therebetween when said portions are in oneposition relative to each other through which said fluid under pressurecan pass for discharge through said passage; said outer portion beingmovable longitudinally with respect to said inner portion out of sealingrelation to such relative position to said inner portion to open saidby-pass.

3. In well apparatus for operation in a well bore: a cylinder; a pistonstructure in said cylinder; means adapted to provide a fluid underpressure in said cylinder on one side of said piston structure to shiftsaid piston structure in said cylinder; said cylinder having a passageon the other side of said piston structure extending from the interiorof said cylinder to its exterior; a shiftable sleeve valve normallyclosing said passage; said piston structure including an inner centralportion sealingly engageable with said sleeve valve to shift said sleevevalve to passage opening position; said piston structure including anouter portion in slidable sealing engagement with said cylinder andadapted to be in sealing relation to said inner portion to prevent fluidflow therebetween; said inner and outer portion being constructed andarranged to provide a bypass therebetween when said portions are in oneposition relative to each other through which said fluid under pressurecan pass for discharge through said passage; said outer portion beingmovable longitudinally by said fluid under pressure with respect to saidinner portion out of sealing relation with said inner portion to suchrelative position to open said by-pass.

4. In well apparatus for operation in a well bore: a cylinder; a pistonstructure in said cylinder; means adapted to provide a fluid underpressure in said cylinder on one side of said piston structure to shiftsaid piston structure in said cylinder; said cylinder having a passageon the other side of said piston structure extending from the interiorof said cylinder to its exterior; shiftable valve means closing saidpassage; said piston structure including a central piston portion; astem depending from said central portion and engageable with said valvemeans to shift said valve means downwardly to passage opening position;said piston structure including an outer portion surrounding said stemand in slidable sealing engagement with said cylinder and adapted to bein sealing relation to said stem to prevent fluid flow therebetween;said stem and outer portion being constructed and arranged to provide aby-pass therebetween when said stem and outer portion are in oneposition relative to each other through which fluid under pressure canpass for discharge through said passage; said outer portion beingmovable longitudinally by said fluid under pressure with respect to saidstem out of sealing relation therewith to such relative position to opensaid by-pass.

5. In well apparatus for operation in a well bore: a lower cylinder; alower piston in said lower cylinder; an upper cylinder secured to saidlower cylinder; an upper piston in said upper cylinder; means providinga fluid passage between said upper cylinder and lower cylinder for anintervening fluid medium adapted to be contained in said upper cylinder,lower cylinder and passage; means supplying a fluid under pressure insaid upper cylinder to shift said upper piston relatively in said uppercylinder and cause said upper piston to force the fluid medium in saidupper cylinder through said passage into said lower cylinder to shiftsaid lower piston relative to said lower cylinder; means providing afluid release passage for releasing said fluid under pressure into thewell bore; valve means normally closing said release passage; said upperpiston including an inner portion engageable with said valve means toshift said valve means to fluid release passage opening position; saidupper piston including an outer portion; said inner and outer portionsbeing constructed and arranged to provide a by-pass therebetween whensaid portions are in one position relative to each other through whichfluid under pressure can pass for discharge through said releasepassage; said outer portion being movable by said fluid under pressurerelative to said inner portion to such position to open said by-pass.

6. In well apparatus for operation in a well bore: a lower cylinder; alower piston in said lower cylinder; an

" upper cylinder secured to said lower cylinder; an upper piston in saidupper cylinder; means providing a fluid passage between said uppercylinder and lower cylinder for an intervening fluid medium adapted tobe contained in said upper cylinder, lower cylinder and passage; meanssupplying a fluid under pressure in said upper cylinder to shift saidupper piston relatively in said upper cylinder and cause said upperpiston to force the fluid medium in said upper cylinder through saidpassage into said lower cylinder to shift said lower piston relative tosaid lower cylinder; means providing a fluid release passage forreleasing said fluid under pressure into the well bore; a sleeve valvenormally closing said release passage; said upper piston including aninner central portion sealingly engageable with said sleeve valve toshift said sleeve valve to release passage opening position; said upperpiston including an outer portion in slidable sealing engagement withsaid upper cylinder and adapted to be in sealing relation to said innerportion to prevent fluid flow therebetween; said inner and outerportions being constructed and arranged to provide a by-passtherebetween when said portions are in one position relative to eachother through which said fluid under pressure can pass for dischargethrough said release passage; said outer portion being movablelongitudinally with respect to said inner portion to said relativeposition to open said by-pass.

References Cited in the file of this patent UNITED STATES PATENTS2,618,343 Conrad Nov. 18, 1952 2,644,530 Baker July 7, 1953 2,681,114Conrad June 15, 1954 2,687,776 Baker Aug. 31, 1954

